Medicare Advantage Risk-Adjustment Payment Methodology
To understand the evolution of the 2023 RADV audit final rule, an understanding of the Medicare Advantage payment methodology is required. While the intention of the Medicare Advantage program was to provide coverage to enrollees who require increased health-care resources, the abuses of the model have resulted in an expanded scope of CMS RADV audits and increased regulatory scrutiny of payers by the Department of Justice.
Unlike Medicare Part B payments, which are based on procedures performed, Medicare Advantage payments are diagnosis driven. A hierarchical condition category (“HCC”) model is used to risk-adjust diagnoses, by grouping ICD-10 diagnosis codes by severity of condition and increased cost of care for treatment of enrollees with chronic diagnoses. The HCCs are additive in nature and produce a risk score. Risk adjustment allows CMS to redirect payments from managed-care organizations that target healthy populations to those that care for the most ill. By risk-adjusting plan payments, CMS can make appropriate payments for enrollees with differences in expected costs. As an enrollee’s risk score increases, the monthly risk-adjusted payment to the Medicare Advantage organization also increases. In this way, the risk-adjustment program compensates Medicare Advantage plans for the additional risk of providing coverage to enrollees expected to require more health-care resources.
CMS Audits of Medicare Advantage Plans
Under its authority to identify waste and mismanagement of federal health program dollars, CMS has been actively conducting audits on risk-adjustment submissions from Medicare Advantage organizations.
There was little to no activity by CMS in terms of Medicare Advantage audits prior to 2019. However, in 2021, CMS recouped $223,043,005 in overpayments from six plans. The overpayment recouped from Humana in one audit totaled $197.7M (comprising 71 percent of the recoveries by the Office of Inspector General for the Department of Health and Human Services (HHS OIG) in 2021). In 2022, CMS recouped $134,739,612 in overpayments from twelve Medicare Advantage plans.
This increased scrutiny stems from the fact that in 2019 the Medicare Advantage program provided health-care coverage for 23 million Americans (accounting for about a third of all Medicare beneficiaries). Health-care coverage under Medicare Advantage plans resulted in a total annual cost of $264 billion of the $758 billion total Medicare program costs spent in fiscal year 2019.
Evolution of the Audit Rule
The discussion below traces the changes in CMS audit methodology and reflects the expansion of RADV audits’ scope over time.
Medicare Advantage Audit Methodology under the 2012 Final Rule
Selection of Plans. The selection of plans for audit in 2012 was stratified. Under CMS’s approach, thirty Medicare Advantage plans were selected annually for audit, typically two to three years after payment. The contracts were targeted based on diagnosis coding intensity, which is the average change in risk score associated with reported beneficiary diagnoses covered by the Medicare Advantage contract. Coding intensity measures the extent to which the estimated medical needs of beneficiaries increase from year to year. The targeted contracts were those whose beneficiaries appeared to get sicker at a relatively rapid rate, based on the information submitted to CMS. Those contracts chosen by coding intensity were divided into three categories: high, medium, and low, with the same number of enrollees for each stratum.
Beneficiary Sampling. The total number of enrollees sampled was up to, but often exceeded (see table below), 201 beneficiaries, with 67 enrollees per stratum. The categories of each stratum were based on the individual risk scores of the enrollees.
Medical Record Collection and Review. After selecting the beneficiaries for review, CMS requested supporting documentation for all risk-adjusted diagnoses submitted in the past year. The Medicare Advantage plans were permitted to submit five medical records per audited risk-adjusted diagnosis. CMS contractors then reviewed the submitted medical records to determine if the medical records supported the diagnosis.
Payment Error Calculation and Extrapolation. When a medical review was completed, CMS extrapolated an error rate for the entire population over the audited period. The extrapolated amount considered the sampling weight of each enrollee. The payment error was calculated by taking the difference between the actual amount paid based on the plan’s submitted diagnoses and the amount that would have been paid based on the RADV-validated diagnoses.
Extrapolation meant that if an error was found during a RADV audit on an HCC, not only were the overpayments recouped on that plan member, but payment was recouped on all members who were in that HCC over the audited year(s). The annual payment error for each sampled enrollee was multiplied by the enrollee’s sampling weight (computed for each stratum). The weighted enrollee annual payment error was summed across all enrollees in the sample to determine the extrapolated payment error.
In its prior final rule in 2012, CMS recognized the need to use an offset, the FFSA, to account “for the fact that the documentation standard used in RADV audits to determine a contract’s payment error (medical records) is different from the documentation standard used to develop the Part C risk-adjustment model (FFS claims).” The FFSA was intended to ensure that the amount due in a RADV audit considered the difference between audit review standards and the errors resulting from unsupported fee-for-service diagnostic codes, creating a permissible level of payment errors and limiting RADV audit recovery to payment errors above the set level. Under that 2012 CMS final rule, the FFSA was used to account for differences in the fee-for-service and Medicare Advantage documentation standards to ensure that there was no bias built in that resulted in underpayment to Medicare Advantage plans.
The 2018 CMS Proposed Rule
Highlights. CMS proposed eliminating the FFSA as part of the revised 2018 RADV audit methodology proposed rule. To support its proposal, CMS cited a 2018 internal study finding “that errors in FFS claims data do not have any systematic effect on the risk scores calculated by the CMS-HCC risk adjustment model, and therefore do not have any systematic effect on the payments made to [Medicare Advantage] organizations.” CMS’s proposed changes to the audit methodology, i.e., the elimination of the FFSA, would allow it to recover payments retroactively from audits conducted for plan years from 2011 forward without an offset.
CMS also asserted its authority to use its discretion to identify different sampling methods and auditing techniques other than a stratified approach, including auditing by sub-cohorts. Auditing by sub-cohorts involves auditing by HCC, targeting diagnoses that CMS views as subject to high rates of improper payment. A sub-cohort represents a grouping of HCCs, such as HCCs 17, 18, and 19—the HCCs for the diagnosis of diabetes and its complications. The 2018 proposed rule recognized that using a sub-cohort method of auditing plans would allow CMS to use smaller sample sizes to calculate extrapolated overpayments.
Litigation. In United Healthcare Insurance v. Becerra, the U.S. Court of Appeals for the D.C. Circuit rejected the United Healthcare challenges to the 2018 CMS RADV rule, finding that there was no valid legal or factual claim that CMS’s overpayment rule failed to comply with actuarial equivalence, affirming CMS’s agency authority to implement the 2018 RADV proposed rule as a final rule.
Audits in 2021 and 2022: Combined Methodology of 2012 and 2018 Audits
Below is a summary of some of the HHS OIG audits performed in 2021 and 2022 that combine the methodology of audits used in both 2012 and 2018 and represent varied approaches to the RADV audit process. CMS’s authority to conduct RADV audits is set out in 42 CFR 422.311 and has been applied by the HHS OIG in its performance of Medicare Advantage compliance audits.